drbd: Allow online change of al-stripes and al-stripe-size

Allow to change the AL layout with an resize operation. For that
the reisze command gets two new fields: al_stripes and al_stripe_size.

In order to make the operation crash save:
1) Lock out all IO and MD-IO
2) Write the super block with MDF_PRIMARY_IND clear
3) write the bitmap to the new location (all zeros, since
   we allow only while connected)
4) Initialize the new AL-area
5) Write the super block with the restored MDF_PRIMARY_IND.
6) Unfreeze all IO

Since the AL-layout has no influence on the protocol, this operation
needs to be beforemed on both sides of a resource (if intended).

Signed-off-by: Andreas Gruenbacher <agruen@linbit.com>
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 5 insertions, 1 deletions

diff --git a/include/linux/drbd.h b/include/linux/drbd.h
index 1b4d4ee1168f..de7d74ab3de6 100644
--- a/include/linux/drbd.h
+++ b/include/linux/drbd.h
@@ -177,7 +177,11 @@ enum drbd_ret_code {
         ERR_NEED_APV_100        = 163,
         ERR_NEED_ALLOW_TWO_PRI  = 164,
         ERR_MD_UNCLEAN          = 165,
-
+        ERR_MD_LAYOUT_CONNECTED = 166,
+        ERR_MD_LAYOUT_TOO_BIG   = 167,
+        ERR_MD_LAYOUT_TOO_SMALL = 168,
+        ERR_MD_LAYOUT_NO_FIT    = 169,
+        ERR_IMPLICIT_SHRINK     = 170,
         /* insert new ones above this line */
         AFTER_LAST_ERR_CODE
 };